Process for the production of textured coatings on plastics surfaces

ABSTRACT

The present invention relates to a process for the production of textured coatings on plastics surfaces using coating compositions based on hydroxyl group-containing binders and polyisocyanates, and using pulverulent texturing agents. 
     The process is characterized in that, initially, a solution of the hydroxyl group-containing binder (I) is mixed with an elastic matting paste (A) comprising 
     a1) from 12 to 25% by weight of a saturated hydroxyl group-containing polyester having a hydroxyl number of from 100 to 160 mg of KOH/g and a number-average molecular weight of from 800 to 2500, 
     a2) from 1 to 4% by weight of a hydroxyl group-containing Cardura-modified acrylate copolymer having a hydroxyl number of from 30 to 250 mg of KOH/g and an acid number of from 0 to 50 mg of KOH/g, 
     a3) from 0 to 3% by weight of cellulose ester, 
     a4) from 35 to 60% by weight of organic solvent, 
     a5) from 12 to 25% by weight of matting agents 
     and if desired catalysts, wetting agents and, if desired, other auxiliaries and additives, the total weight of the elastic matting paste (A) being in each case 100% by weight, 
     the elastic matting paste (A) being sieved if desired before or after being mixed with the solution of the hydroxyl group-containing binder (I), the mixture is subsequently mixed together with polyisocyanates (II) as crosslinking agents, other organic solvents if desired and with the pulverulent texturing agent, the resulting coating composition is applied to the plastics substrate, and the coating is dried.

This application is a 371 of PCT/EP94/01590 filed May 17, 1994.

The present invention relates to a process for the production oftextured coatings on plastics surfaces, using coating compositions basedon hydroxyl group-containing binders and polyisocyanates as crosslinkingagents and using pulverulent texturing agents.

Plastics surfaces, for example car bumpers, are often coated withtexturing, matting coatings, in order to obtain textured plasticssurfaces. It is known to employ coating compositions containing organicsolvents and based on hydroxyl group-containing binders andpolyisocyanates, which contain additives in paste form, containingpulverulent texturing agents, and matting agents in order to obtaintextured surfaces of plastics components on cars, especially forrefinishing. The texturing agent employed in this context is, forexample, ground polypropylene. The matting agent used is, for example,silicic acid. With the aid of the matting agent, the coating compositionintended for the textured surface is adjusted to the degree of gloss ofthe plastics surface. To ensure good adhesion to the plastics substrate,elasticized binders are employed.

However, the problem which occurs with the previously known texturingcoating compositions for plastics components on cars is that dried-onparticles can fall back into the paint from the can edge of therespective containers and, as so-called bittiness, can interfere withprocessing and lead to paint defects. It is not possible to sieve offthese dried-on product particles before processing, i.e. before theapplication of the coating compositions, since otherwise the pulverulenttexturing agent would also be removed.

The object of the present invention was therefore to avoid theabove-described disadvantages of the previously known texturing coatingcompositions. The intention was to provide a process for the productionof textured coatings on plastics surfaces, especially for refinishing,using coating compositions based on hydroxyl group-containing bindersand polyisocyanates, this process being intended to enable the sieveremoval, shortly before application, of any dried product particlesformed. The coating compositions used in the process were to containpulverulent texturing agents and the matting agents required to adjustthe desired degree of gloss. In addition, the process was to enabletrouble-free incorporation of the pulverulent texturing agents into theplastics-coating compositions.

The object of the present invention is surprisingly achieved by aprocess for the production of textured coatings on plastics surfaces,using coating compositions based on hydroxyl group-containing bindersand polyisocyanates as crosslinking agents, and using pulverulenttexturing agents. The process according to the invention ischaracterized in that, initially, a solution of the hydroxylgroup-containing binder (I) is mixed with an elastic matting paste (A)comprising

a1) from 12 to 25% by weight, preferably from 16 to 21% by weight, of asaturated hydroxyl group-containing polyester having a hydroxyl numberof from 100 to 160 mg of KOH/g and a number-average molecular weight offrom 800 to 2500,

a2) from 1 to 4% by weight, preferably from 1.8 to 2.6% by weight, of ahydroxyl group-containing Cardura-modified acrylate copolymer having ahydroxyl number of from 30 to 250 mg of KOH/g and an acid number of from0 to 50 mg of KOH/g,

a3) from 0 to 3% by weight of cellulose ester,

a4) from 35 to 60% by weight, preferably from 45 to 55% by weight, oforganic solvent,

a5) from 12 to 25% by weight, preferably from 15 to 22% by weight, ofmatting agents

and if desired catalysts, wetting agents and, if desired, otherauxiliaries and additives, the total weight of the elastic matting paste(A) being in each case 100% by weight,

the elastic matting paste (A) being sieved if desired before or afterbeing mixed with the solution of the hydroxyl group-containing binder(I), the mixture is subsequently mixed together with polyisocyanates(II) as crosslinking agents, other organic solvents if desired and withthe pulverulent texturing agent, the resulting coating composition isapplied to the plastics substrate, and the coating is dried.

Suitable hydroxyl group-containing binders (I) include both resinsproduced by addition polymerization and those produced by condensationpolymerization. Particularly preferred resins are hydroxylgroup-containing polyacrylate resins having OH numbers of from 30 to 250mg of KOH/g and acid numbers of from 0 to 50 mg of KOH/g. Thenumber-average molecular weights of the preferred hydroxylgroup-containing polyacrylates are conventionally between 1,000 and10,000, in each case measured by GPC against a polystyrene standard. Thehydroxyl groups are introduced into the polyacrylate resin by usingmonomers which contain hydroxyl groups. Generally from 20 to 60% byweight, based in each case on the overall weight of the monomersemployed, of at least one hydroxyl group-containing, ethylenicallyunsaturated monomer are employed. Suitable hydroxyl group-containing,ethylenically unsaturated monomers are hydroxyalkyl esters ofα,β-unsaturated carboxylic acids containing primary orsecondary-hydroxyl groups. Examples of suitable hydroxyalkyl esters ofα,β-unsaturated carboxylic acids containing primary hydroxyl groups arehydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate,hydroxyamyl acrylate, hydroxyhexyl acrylate, hydroxyoctyl acrylate andthe corresponding methacrylates. Examples of hydroxyalkyl esters whichcan be used and which have a secondary hydroxyl group are2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutylacrylate and the corresponding methacrylates. It is of course alsopossible in each case to employ the corresponding esters of otherα,β-unsaturated carboxylic acids, for example of crotonic acid and ofisocrotonic acid. The hydroxyl group-containing monomer may be, at leastin part, a reaction product of one mole of hydroxyethyl acrylate and/orhydroxyethyl methacrylate and on average 2 mol of ε-caprolacton.Furthermore, the hydroxyl group-containing monomer employed may also, atleast in part, be a reaction product of acrylic acid and/or methacrylicacid with the equivalent amount of a glycidyl ester of a carboxylic acidhaving a tertiary α carbon atom. Examples of other suitable comonomersare aromatic vinyl compounds, for example styrene, vinyltoluenes,α-methylstyrene, chlorostyrenes, o-, m- or p-methylstyrene,2,5-dimethylstyrene, p-methoxystyrene, p-tert-butyl-styrene,p-dimethylaminostyrene, p-acetamidostyrene and m-vinylphenol. Alsosuitable are other ethylenically unsaturated, copolymerizable monomers,for example alkyl esters of olefinically unsaturated carboxylic acids.Examples of these are methyl (meth)acrylate, ethyl (meth)acrylate, butyl(meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate,pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate,cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl(meth)acrylate, 3,5,5-trimethylhexyl (meth)acrylate, decyl(meth)acrylate, dodecyl (meth)acrylate, hexadecyl (meth)acrylate,octadecyl (meth)acrylate, and octadecenyl (meth)acrylate and thecorresponding esters of maleic, crotonic, isocrotonic, vinylacetic anditaconic acid. Other suitable ethylenically unsaturated comonomers arealkoxyethyl acrylates, aryloxyethyl acrylates and the correspondingmethacrylates. In order to improve the compatibility, it is alsopossible to copolymerize small quantities of carboxyl group-containingmonomers. Examples of suitable carboxyl group-containing monomers areunsaturated carboxylic acids, for example acrylic acid, methacrylicacid, itaconic acid, crotonic acid and half-esters of maleic and fumaricacid. The polymerization of the monomer components is carried out in thepresence of organic solvents with the exclusion of oxygen, for exampleby operating under a nitrogen atmosphere. The polymerization reaction iscarried out at temperatures of from about 100° to 180° C., usingappropriate polymerization initiators and--if desired--polymerizationregulators. The polymerization is preferably carried out in high-boilingorganic solvents which are inert with respect to the monomers employed.

As hydroxyl group-containing binders (I) it is particularly preferred toemploy acrylate copolymers having a hydroxyl number of from 30 to 250 mgof KOH/g which are obtainable by copolymerization of

(Ia) Hydroxyalkyl esters of α,β-ethylenically unsaturated carboxylicacids,

(Ib) if desired, vinyl esters of monocarboxylic acids,

(Ic) if desired, ethylenically unsaturated carboxylic acids, and

(Id) other ethylenically unsaturated monomers,

where component (Ia) employed comprises, at least in part, reactionproducts of acrylic acid and/or methacrylic acid with the glycidyl esterof a carboxylic acid having a tertiary α carbon atom. Examples of thehydroxyalkyl esters of α,β-ethylenically unsaturated carboxylic acidshave already been described above.

In this context, component (Ia) used comprises, at least in part,reaction products of acrylic acid and/or methacrylic acid with theequivalent quantity of a glycidyl ester of a carboxylic acid having atertiary α,β carbon atom. Glycidyl esters of highly branchedmonocarboxylic acids are available under the tradename "Cardura". Theacrylic acid or methacrylic acid can be reacted with the glycidyl esterof a carboxylic acid having a tertiary α carbon atom before, during orafter the polymerization reaction.

If desired, it is possible to employ vinyl esters of monocarboxylicacids as comonomers (component Ib). Here it is preferable to employvinyl esters of α-branched monocarboxylic acids having from 5 to 15carbon atoms per molecule. Of particular preference, moreover, is thevinyl ester of p-tert-butylbenzoic acid. Examples of other suitablevinyl esters are vinyl acetate and vinyl propionate.

Examples of suitable components (Ic) and (Id) have already beendescribed above.

Suitable hydroxyl group-containing binders (I) are, in addition,polyesters which contain hydroxyl groups. Also suitable arepolyester-modified polyacrylates, for example those described in DE-A-4024 204.

Examples of suitable polyisocyanates (II) are:

Aromatic isocyanates, for example 2,4- and 2,6-tolylene diisocyanate andmixtures thereof, 4,4'-diphenylmethane diisocyanate, m-phenylene,p-phenylene, 4,4-biphenyl, 1,5-naphthalene, 1,4-naphthalene,4,4-toluidine and xylylene diisocyanate, and substituted aromaticsystems, for example dianisidine diisocyanates, 4,4-diphenyl etherdiisocyanates or chlorodiphenylene diisocyanates, and more highlyfunctional aromatic isocyanates, for example 1,3,5-triisocyanatobenzene,4,4',4"-triisocyanatotriphenylmethane, 2,4,6-triiso-cyanatotoluene and4,4'-diphenyldimethylmethane 2,2',5,5'-tetraisocyanate; cycloaliphaticisocyanates, for example 1,3-cyclopentane, 1,4-cyclohexane,1,2-cyclohexane and isophorone diisocyanate; aliphatic isocyanates, forexample trimethylene, tetramethylene, pentamethylene, hexamethylene andtrimethylhexamethylene 1,6-diisocyanate and trishexamethylenetriisocyanate. It is preferred to employ diisocyanates having isocyanategroups of differing reactivity, for example isophorone diisocyanate.Also suitable are isocyanate prepolymers of relatively high molecularmass. Compounds which can be mentioned in this context are adducts oftolylene diisocyanate and trimethylol propane, a biuret formed from 3molecules of hexamethylene diisocyanate, and the trimers ofhexamethylene diisocyanate and of3,5,5-trimethyl-1-isocyanato-3-isocyanatomethylcyclohexane.

The quantity of crosslinking agent employed here is chosen so that theratio of the isocyanate groups of component (II) to the sum of thehydroxyl groups of the coating composition is in the range from 1:3 to3:1.

The coating compositions contain one or more organic solvents. Thesesolvents are conventionally employed in quantities of from 20 to 65% byweight, based in each case on the overall weight of the coatingcomposition. Examples of suitable solvents are relatively highlysubstituted aromatics, for example solvent naphtha, heavy benzene,various Solvesso grades, various Shellsol grades and Deasol, andrelatively high-boiling aliphatic and cycloaliphatic hydrocarbons, forexample various white spirits, mineral oil of turpentine, tetralin anddecalin and various esters, for example ethylglycol acetate, butylglycolacetate, ethyldiglycol acetate and the like.

In accordance with the process according to the invention, a solution ofthe hydroxyl group-containing binder (I) is initially mixed with anelastic matting paste (A); the elastic matting paste (A), if necessary,being sieved before or after being mixed with the binder solution. Insome cases the sieving procedure can of course be dispensed with, ifthere are no dried interfering particles.

As component a1), this matting paste contains from 12 to 25% by weight,preferably from 16 to 21% by weight, of a saturated, hydroxylgroup-containing polyester having a hydroxyl number of from 100 to 160mg of KOH/g and a number-average molecular weight of from 800 to 2,500.The branching of the polyester should amount to from 0.2 to 0.6 mol/kg.These polyesters are tough, flexible polyester grades. For thepreparation of the polyesters, it is preferred to employ aromaticpolycarboxylic acids in combination with aliphatic polycarboxylic acids.Examples are phthalic acid, isophthalic acid, terephthalic acid,halophthalic acids such as tetrachloro- or tetrabromophthalic acid,adipic acid, glutaric acid, azelaic acid, sebacic acid, fumaric acid,maleic acid, trimellitic acid, pyrromellitic acid and the like.

Also suitable are the esterifiable derivatives of the abovementionedpolycarboxylic acids, for example their mono- or polyesters withaliphatic alcohols having from 1 to 4 carbon atoms or hydroxy alcoholshaving from 1 to 4 carbon atoms. In addition, it is also possible toemploy the anhydrides of the abovementioned acids, where these exist. Ifdesired, cycloaliphatic carboxylic acids can also be employed.

Together with the polycarboxylic acids, it is also possible to employmonocarboxylic acids such as, for example, benzoic acid,tert-butylbenzoic acid, lauric acid, isononanoic acid and fatty acids ofnaturally occurring oils.

Suitable alcohol components for the preparation of the hydroxylgroup-containing polyesters are polyhydric alcohols such as ethyleneglycol, propanediols, butanediols, hexanediols, neopentylglycol,diethylene glycol, cyclohexanediol, cyclohexanedimethanol,trimethylpentanediol, ethylbutylpropanediol, ditrimethylolpropane,trimethylolethane, trimethyolpropane, glycerol, pentaerythritol,dipentaerythritol, trishydroxyethyl isocyanurate, polyethylene glycoland polypropylene glycol, together if desired with monohydric alcohols.It is preferred to employ linear long-chain polyols, for examplehexane-1,6-diol. As a more highly functional alcohol, trimethylolpropaneis preferably used.

The acid number of the hydroxyl group-containing polyesters should notbe greater than 5 mg of KOH/g.

The hydroxyl group-containing polyesters are prepared by the knownmethods of esterification, for example as described in Ullmann'sEnzyklopadie der technischen Chemie Ullmann's Encyclopedia of IndustrialChemistry!, volume 14, pages 80 to 106 (1963).

This reaction is usually carried out at temperatures of between 180° and280° C., in the presence if desired of a suitable esterificationcatalyst. Conventionally, the polyesters are prepared in the presence ofsmall quantities of a suitable solvent as entraining agent.

As component a2), the matting paste (A) contains from 1 to 4% by weight,preferably from 1.8 to 2.6% by weight, of a Cardura-modified acrylatecopolymer which contains hydroxyl groups and has a hydroxyl number offrom 30 to 250 mg of KOH/g and an acid number of from 0 to 50 mg ofKOH/g. The hydroxyl groups are incorporated into the Cardura-modifiedacrylate resin by using hydroxyl group-containing monomers. It is usualto employ from 20 to 60% by weight, based in each case on the overallweight of the monomers employed, of at least one hydroxylgroup-containing ethylenically unsaturated monomer.

Suitable hydroxyl group-containing monomers are hydroxyalkyl esters ofα,β-ethylenically unsaturated carboxylic acids containing primary orsecondary hydroxyl groups. It is of course also possible to use mixturesof hydroxyalkyl esters containing primary and secondary hydroxyl groups.Examples of suitable hydroxyalkyl esters of α,β-ethylenicallyunsaturated carboxylic acids, containing primary hydroxyl groups, arehydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate,hydroxyamyl acrylate, hydroxyhexyl acrylate, hydroxyoctyl acrylate andthe corresponding methacrylates. Examples which may be mentioned ofhydroxyalkyl esters which contain a secondary hydroxyl group and whichit is possible to use are 2-hydroxypropyl acrylate, 2-hydroxybutylacrylate, 3-hydroxybutyl acrylate and the corresponding methacrylates.

It is of course also possible to employ in each case the correspondingesters of other α,β-ethylenically unsaturated carboxylic acids, forexample those of crotonic acid and of isocrotonic acid. Component a2) isa Cardura-modified acrylate copolymer, i.e. the hydroxylgroup-containing monomer employed at least in part is a reaction productof acrylic acid and/or methacrylic acid with the equivalent amount of aglycidyl ester of a carboxylic acid having a tertiary α carbon atom.These glycidyl esters of highly branched monocarboxylic acids areavailable under the tradename "Cardura". The reaction of the acrylicacid or methacrylic acid with the glycidyl ester of a carboxylic acidhaving a tertiary α carbon atom may be carried out before, during orafter the polymerization.

Other suitable comonomers for the preparation of the Cardura-modifiedacrylate copolymers are:

aromatic vinyl compounds, for example styrene, vinyltoluenes,α-methylstyrene, chlorostyrenes, o-, m- and p-methylstyrene,2,5-dimethylstyrene, p-methoxystyrene, p-tert-butylstyrene,p-dimethylaminostyrene, p-acetamidostyrene and m-vinylphenol; alkylesters of olefinically unsaturated carboxylic acids, such as methyl(meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isopropyl(meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, isoamyl(meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate,2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, 3,5,5-trimethylhexyl(meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, hexadecyl(meth)acrylate, octadecyl (meth)acrylate, octadecenyl (meth)acrylate andthe corresponding esters of maleic, crotonic, isocrotonic, vinyl aceticand itaconic acid; alkoxyethyl acrylates, aryloxyethyl acrylates and thecorresponding methacrylates, for example butoxyethyl (meth)acrylate andphenoxyethyl (meth)acrylate; carboxyl group-containing monomers, forexample acrylic acid, methacrylic acid, itaconic acid, crotonic acid andhalf-esters of maleic and fumaric acid; unsaturated compounds containingtertiary amino groups, for example 2-vinylpyridine, vinylpyrroline,vinylquinoline, vinylisoquinoline, N,N'-dimethylaminoethyl vinyl etherand 2-methyl-5-vinylpyridine.

The hydroxyl group-containing, Cardura-modified polyacrylates aregenerally produced by solution polymerization. Such processes are knownin the literature and described, for example, earlier in thisapplication.

The matting paste (A) contains from 0 to 3% by weight of a celluloseester (component a3)). Examples of suitable cellulose esters arecellulose nitrate and cellulose esters of organic acids such as aceticacid, propionic acid and butyric acid, with cellulose acetobutyratebeing used with preference.

The elastic matting paste A) contains from 35 to 60% by weight,preferably from 45 to 55% by weight, of organic solvent. Examples ofsuitable solvents are aromatic compounds with relatively high degrees ofsubstitution, for example solvent naphtha, heavy benzene, variousSolvesso grades, various Shellsol grades and Deasol, and relativelyhigh-boiling aliphatic and cycloaliphatic hydrocarbons, for examplevarious white spirits, mineral oil of turpentine, tetralin and decalinand various esters, for example butyl acetate, ethylglycol acetate,butylglycol acetate, ethyldiglycol acetate and the like.

As component a5), the elastic matting paste A) contains from 12 to 25%by weight, preferably from 15 to 22% by weight, of matting agent.Suitable matting agents are commercially available silicic acids, suchas pyrogenic silicic acid or silica gels.

In addition, the elastic matting paste A) may if desired containcatalysts, wetting agents and--if desired--other paint auxiliaries andadditives. Suitable catalysts are organotin compounds.

Suitable wetting agents are polymer wetting agents based on polyacrylateand/or polyester. Examples of suitable commercial products are Disperbyk160, Disperbyk 161 (Manufacturer: Byk-Chemie) and Efka 400 and Efka 401(Manufacturer: Efka).

Other suitable paint auxiliaries and additives are leveling agents suchas silicone oils, plasticizers such as phosphates and phthalates,viscosity-controlling additives, UV absorbers, light stabilizers and, ifdesired, fillers.

The elastic matting paste is prepared in a known manner by the mixingand, if desired, dispersion of the individual components.

The mixing ratio between the organic binder solution and the elasticmatting paste (A) is, for example, 1:1.

Shortly before application the organic binder solution is mixedthoroughly with the elastic matting paste and stored in conventionalcontainers until further use. A sieving procedure is then possibleemploying the high-speed screens which are conventionally used, in orderto remove any contaminations, for example dried-on product particles. Itis of course also possible to subject the elastic matting paste (A) to asieving procedure prior to mixing with the binder solution. However, itis preferred to carry out any sieving procedure necessary only after themixing of the components.

Shortly before application of the coating composition, the mixture ofthe organic binder solution and of the elastic matting paste (A) ismixed together with the polyisocyanate crosslinking agents (II), withother organic solvents if desired, and with the pulverulent texturingagent.

Suitable pulverulent texturing agents are ground plastics, for exampleground polyamide and ground polypropylene. Other suitable examples areground sand and ground glass. Appropriate commercial polypropylenetexturing agents are available under the tradename Propyltex 20S, 50,100S, 140S, 200S, 200SF and 325S (Manufacturer: Micro Powders, Inc.),Texture 5388, 5380, 5384, 5382 and 5386 (Manufacturer: Shamrock).

Appropriate hollow glass microballs, which can be used as texturingagents, are available under the tradename Scotchlite Glass Bubbles(Manufacturer: 3 M Deutschland GmbH).

The particle size of the texturing agent used is selected in dependenceon the intended use. The average particle size of the texturing agent ispreferably in the range from 40 to 250 lm.

Conventionally, the texturing agent is employed in a proportion of from3 to 8% by weight, lacuna! preferably on the overall weight of thefinished coating composition. However, deviations from this are possiblein dependence on the intended use.

The amount of polyisocyanate crosslinking agent (II) is chosen such thatthe number of free hydroxyl groups to the number of isocyanate groups isin the range from 3:1 to 1:3.

If desired, organic solvents are additionally added to the mixture toadjust the coating composition to an appropriate application viscosity.The coating composition is conventionally applied to the plasticssubstrate by spraying.

The process according to the invention is preferably employed for therefinishing of plastics surfaces on cars, for example bumpers.

The process offers the particular advantage that the coating compositioncan be subjected to a sieving procedure shortly before application, inorder to remove dried-on product particles which could lead to paintdefects. Moreover, the addition of the texturing agent as a concentrateoffers the advantage of enabling the flexible addition of theappropriate quantity of a texturing agent to the coating composition,depending on the set of requirements.

The invention is illustrated in more detail below on the basis of twoexemplary embodiments. In these embodiments parts are by weight unlessotherwise indicated.

1. PREPARATION OF THE ELASTIC MATTING PASTES A1) AND A2)

1.1 Preparation of a saturated, hydroxyl group-containing polyester (a1)

By a conventional polyester preparation process, a saturated, hydroxylgroup-containing polyester is prepared from 1.0 mol of hexane-1,6-diol,0.2 mol of trimethylolpropane, 0.65 mol of isophthalic acid, 0.1 mol ofphthalic anhydride and 0.25 mol of adipic acid. The polyester has an OHnumber of 145 mg of KOH/g and an acid number of 1 mg of KOH/g. A 70%solution of the polyester in butyl acetate is prepared.

1.2 Preparation of a hydroxyl group-containing, Cardura-modifiedacrylate copolymer (a2)

A 4-1 stainless steel vessel is charged with:

    ______________________________________                                        Xylene                326.65  parts                                           1-methoxypropyl 2-acetate                                                                           326.65  parts                                           Glycidyl ester of Versatic acid                                                                     190.00  parts                                           ______________________________________                                    

The mixture is heated to 140° C. and then the following components aremetered in from the monomer tank over the course of 3 h:

    ______________________________________                                        t-butyl acrylate      200    parts                                            Styrene               150    parts                                            Hydroxypropyl acrylate                                                                              130    parts                                            Butanediol monoacrylate                                                                             120    parts                                            Methyl methacrylate   140    parts                                            Acrylic acid          70     parts                                            Mercaptoethanol       10     parts                                            ______________________________________                                    

The following components are metered in from the initiator tank at auniform rate over the course of 3.5 h:

    ______________________________________                                        Xylene                 12    parts                                            1-methoxypropyl 2-acetate                                                                            12    parts                                            Dicumyl peroxide       6     parts                                            ______________________________________                                    

The addition of both feeds (monomer and initiator) is simultaneous, andduring the polymerization the temperature in the vessel is maintained at140° C. Subsequently, polymerization is continued for a further 3 h.

Solids content: 60.8%

Viscosity (50%, dpas): 1.90

Acid number: 17.6

Matting pastes A1) and A2) are prepared by mixing and dispersing thefollowing components:

    ______________________________________                                                            A1)  A2)                                                  ______________________________________                                        OH polyester (a1), based                                                                            18.8   19.5                                             on solids                                                                     Cardura-modified OH polyacrylate                                                                    2.2    2.2                                              (a2), based on solids                                                         Cellulose acetobutyrate                                                                             1.2    1.2                                              Silicic acid (Aerosil 380)                                                                          0.5    0.5                                              Commercial matting agent                                                                            19.0   19.0                                             Light stabilizer      1.7    1.7                                              Silicone oil          1.0    1.0                                              Dibutyltin dilaurate  0.2    0.2                                              Diethylethanolamine   4.0    4.0                                              Commercial polymer    2.7    --                                               wetting agent                                                                 Xylene                4.0    4.0                                              Solvent naphtha       2.8    2.8                                              Butylglycol acetate   0.1    0.1                                              Butyl acetate 98/100  41.8   43.8                                             ______________________________________                                    

2. EXAMPLE 1 AND 2

100 parts of the OH polyacrylate having the designation 21-1240,"Glassodur-PUR-Acryl-Autolack", black, Manufacturer: BASF Lacke+FarbenAG, are thoroughly mixed with 100 parts of the matting paste A1),(Example 1) and A2) (Example 2).

Any dried-on product particles which form are removed by sieving(high-speed screen).

100 parts of the resulting mixtures are thoroughly mixed in each casewith 50 parts of the polyisocyanate curing agent "Glassodur-MS-Harter",normal, 929-73 from BASF Lacke+Farben AG and 10 parts of a groundpolypropylene (Propyltex 140S, Micro Powders Inc.). Each mixture isadjusted to a spray viscosity of from 20 to 22 sec./DIN 4 cup.

Each mixture is applied to a plastics substrate with a dry filmthickness of 25 lm. After a flash-off for 10 min., a further spray passis carried out (dry film thickness 25 lm). The coated substrate is thendried at 60° C. for 30 minutes.

Two textured coatings are obtained.

We claim:
 1. Process for the production of textured coatings on plasticsurfaces comprising the steps of:A) preparing an elastic matting pastecomprisinga1) from 12 to 25% by weight of a saturated hydroxylgroup-containing polyester having a hydroxyl number of from 100 to 160mg of KOH/g and a number-average molecular weight of from 800 to 2500,a2) from 1 to 4% by weight of a hydroxyl group-containing acrylatecopolymer polymerized from a mixture of monomers that comprises thereaction product of a glycidyl ester of a carboxylic acid having atertiary α-carbon atom with one member selected from the groupconsisting of acrylic acid, methacrylic acid, and mixtures thereof;wherein said acrylate copolymer has a hydroxyl number of from 30 to 250mg of KOH/g and an acid number of from 0 to 50 mg of KOH/g, a3) from 0to 3% by weight of cellulose ester, a4) from 35 to 60% by weight oforganic solvent, and a5) from 12 to 25% by weight of matting agents, thetotal weight of the elastic matting paste (A) being in each case 100% byweight; B) mixing a solution of a hydroxyl group-containing binder andthe matting paste together, wherein at least one the matting paste andthe binder-matting paste mixture is sieved to remove dried particles; C)combining the binder-matting paste mixture with polyisocyanates ascrosslinking agents and a pulverulent texturing agent to form a coatingcomposition; D) applying the resulting coating composition to a plasticsubstrate, and E) drying the applied coating.
 2. Process according toclaim 1, wherein the texturing agent is selected from the groupconsisting of ground plastic, glass and sand.
 3. Process according toclaim 1 wherein the average particle size of the texturing agent is from40 to 250 μm.
 4. Process according to claim 1, wherein the hydroxylgroup-containing binder (I) is an acrylate copolymer having a hydroxylnumber of from 30 to 250 mg of KOH/g which is obtained bycopolymerization of(Ia) Hydroxyalkyl esters of α,β-ethylenicallyunsaturated carboxylic acids,and optionally compounds selected from thegroup consisting of (Ib) vinyl esters of monocarboxylic acids, (Ic)ethylenically unsaturated carboxylic acids, (Id) other ethylenicallyunsaturated monomers, and mixtures thereof,where component (Ia)comprises, at least in part, reaction products of acrylic acid and/ormethacrylic acid with the glycidyl ester of a carboxylic acid having atertiary A carbon atom.
 5. Process according to claim 1, comprisingapplying a refinish coating composition as defined in claim 1 to plasticsurfaces on cars.
 6. Process according to claim 1, wherein the coatingapplied further comprises components selected from the group consistingof catalysts, wetting agents, solvents, and mixtures thereof.
 7. Processaccording to claim 1 wherein the matting paste A) is sieved before beingmixed with the solution of the hydroxyl group-containing binder (I). 8.Process according to claim 1 wherein the matting paste A) is sievedafter being mixed with the solution of the hydroxyl group-containingbinder (I).
 9. Process for the production of textured coatingcompositions based on hydroxyl group-containing binders andpolyisocyanate crosslinking agents, using pulverulent texturing agents,wherein the process comprisesinitially mixing a solution of the hydroxylgroup containing binder with an elastic matting paste (A) comprisinga1)from 16 to 21% by weight, of a saturated hydroxyl group-containingpolyester having a hydroxyl number of from 100 to 160 mg of KOH/g and anumber-average molecular weight of from 800 to 2500, a2) from 1.8 to2.6% by weight, of a hydroxyl group-containing acrylate copolymerpolymerized from a mixture of monomers that comprises the reactionproduct of a glycidyl ester of a carboxylic acid having a tertiary∝-carbon atom with one member selected from the group consisting ofacrylic acid methacrylic acid, and mixtures thereof: wherein saidacrylate copolymer has a hydroxyl number of from 30 to 250 mg of KOH/gand an acid number of from 0 to 50 mg of KOH/g, a3) from 0 to 3% byweight of cellulose ester, a4) from 45 to 55% by weight, of organicsolvent, a5) from 15 to 22% by weight, of matting agents the totalweight of the elastic matting paste (A) being in each case 100% byweight, subsequently mixing the binder and matting paste mixturetogether with polyisocyanate crosslinking agents, and the pulverulenttexturing agent, followed by applying the resulting coating compositionto a plastic substrate, and drying the coating.